Controllable reciprocator



Sep 1966 w. n. GAUTHIER ETAL 3,274,860

, CONTROLLABLE RECIPROCATOR Filed March 23, 1964 2 Sheets-Sheet 1 53 5a p 5? A V 6/ 6'2 INVENTORS: I I I'LLIAM l7. EAUTHIER, I B BY Ear-JAR]: K0 CK.

Sept. 27, 1966 Filed March 25, 1964 W. D. GAUTHIER ETA]...

CONTROLLABLE RECIPROCATOR 2 Sheets-Sheet 2 INVENTORS: I/YJLLIAM Z7. GAUTHJEH, BY EHHAHD KUUK.

United States Patent 3,274,860 CONTROLLAELE RECIPROCATOR William D. Gauthier, Sylvania Township, Lucas County, and Erhard Kock, Toledo, Ohio, assignors to The De Vilbiss Company, Toledo, Ohio, a corporation of Ohio Filed Mar. 23, 1964, Ser. No. 353,837 3 Claims. (Cl. 74829) This invention relates to a mechanism for imparting a controllable reciprocatory movement to one or a plurality of coating material issuing devices. The invention is primarily directed to a means to reciprocate spray guns for the deposition of coating materials such as paints and lacquers, although it is readily usable with apparatus for depositing dry coating materials as well. The specific application of the invention is directed to the reciprocation of electrostatically charged spray guns for liquid coating materials.

There have recently been developed electrostatic coating material issuing devices which will exhibit a fairly large round deposition pattern when held stationary against a stationary target. The density of the pattern, that is the amount of paint deposited per square inch, is not uni-form from side to side or from top to bottom. The pattern is somewhat more dense in the middle and in an annular band than in the intervening space between the central dense area and the band. However, it is known in the art that the work may be moved laterally on a conveyor across the intervening space in front of a gun and such movement may result in an acceptably uniform deposition pattern. Further, the distribution of the deposited spray is such that the pattern lends itself to blending with the patterns of neighboring guns in an array of a plurality of guns to provide a coating on a workpiece having a satisfactory degree of thickness uniformity.

It is also known in the art that reciprocation of one or a plurality of spray guns can improve the deposition uniformity. This is particularly true in electrostatically charged guns. Reciprocation in this instance is done primarily for improving uniformity and blending the patterns of several guns. In non-electrostatic painting systems movement of the gun is usually done for the purpose of making a gross increase in the area of the surface covered by the material issuing from the gun.

The present invention provides a reciprocator on which one or more electrostatically charged spray guns may be mounted. Inasmuch as a single electrostatic installation will frequently be called upon to coat many types and sizes of workpieces, it is desirable to be able to make adjustments in the stroke of the reciprocator on which the electrostatic spray guns are mounted. Two major adjustments that are required are the length of the reciprocating stroke and the elevation of the mid-point of such stroke. It is desirable that provision be made for making these adjustments without shutting the machine down or in any way interrupting the machine operation.

The primary object of the present invention, therefore, is to provide a controllable reciprocator for mounting one or a plurality of electrostatic spray guns which can be adjusted while in operation to vary the length of the reciprocating stroke and the center of the reciprocating motion.

Other advantages and further objects of the invention will become apparent from the following detailed description of a preferred form and embodiment thereof, reference being had to the accompanying drawings, in which:

FIGURE 1 is a side elevational view, partially diagrammatic, showing a mechanism embodying the present invention;

FIG. 2 is a view, with parts in section, taken on line 22 of FIG. 1;

3,274,860 Patented Sept. 27, 1966 FIG. 3 is a fragmentary view, with parts in section, taken on line 3-3 of FIG. 1;

FIG. 4 is a diagram indicating the change in motion in response to one adjustment of the mechanism of the present invention;

FIG. 5 is a diagram indicating the result of a second adjustment of the mechanism of the present invention;

FIG. 6 is a sectional view taken on line 66 of FIG.1;

FIG. 7 is a sectional view taken on line 7-7 of FIG. 6; and

FIG. 8 is a fragmentary sectional view taken on line -8-8 of FIG. 1.

The present invention is shown in a preferred embodiment in the drawings, and comprises a base 10 mounted on wheels 11 so that the apparatus of the present invention is capable of adjustment to and from the plane of a workpiece carried by a conveyor across the space ahead of the spray gun, as is common practice. A vertical support, which is shown as a channel member 12 extends upwardly from the base 10. A lower insulating arm 13 is pivoted to the support 12, in a manner hereinafter described, and, at its upper end, the support 12 carries an upper movable insulating arm 14 pivoted on a transverse pin 15 and in a position parallel to the lower arm 13.

The arms 13 and 14, at their outer ends, carry a gun mounting stem 16. The spray guns carried thereby are indicated at G and may be of any suitable type. Electrostatic charging of the guns is accomplished by a power pack P. The stem 16 has spaced upper and lower brackets 17 and 18 that are pinned to the respective arms 13 and 14 so that the stem will follow an essentially vertical reciprocatory movement as the arms 13 and 14 pivot about their respective centers. It is desirable that the length of the arms 13 and 14 be such that when the apparatus is in motion there is no significant change in the distance between the spray guns and the work. This distance need not vary more than an inch or so with a reciprocator stroke length of fifteen inches.

The lower insulating arm 13 is received in a box frame member 19, and a transverse bearing or shaft 20 extends through the box frame member and is journaled in pillow blocks 21 at each side, bolted to the channel support 12.

The box frame member 19 also forms the forward connecting point for a drive arm 22 which extends rearwardly of the support member 12 and is thus functionally integral with the lower insulating arm 13.

In the preferred execution of the invention, the drive arm 22 is made arcuate and is provided with gear teeth 24 on its lower edge, the drive arm being essentially rectangular in cross section. The center of the arc of the arm 22 is about at the neutral position of the drive means therefor. An adjusting pinion 25 meshes with the drive arm gear teeth 24 and is carried by a yoke 26 which extends over the arm 22 and is made up of spaced plates which lie closely adjacent the side walls of the arm 22. The yoke 26 is driven by a connecting rod 27 and imparts movement to the drive arm 22 in a manner hereinafter described. As best shown in FIGS. 2 and .3 the connecting rod 27 has a bearing connection 28 at its upper end with a pin 29 extending laterally of the bearing and received through the yoke 26 with a spacer collar 30 between the depending arms of the yoke and the entire pin, yoke and collar assembly being held together by a clamp nut 31. Anti-friction rollers 32 and 33 are provided to facilitate the movement of the yoke with respect to the arm during adjustment as hereinafter described.

The adjusting pinion 25 is provided with a hub extension 35 having a cross slot 36 in its exposed face which cooperates with a cross tooth 37 on a crank 38. The crank is provided with a laterally extending handle 39 ice by which its position may be changed by the operator. When the cross tooth 37 is engaged in the cross slot 36 the operator can turn the adjusting gear 25 along the teeth 24 formed on the lower side of the drive arm 22 and in this manner change the effective point of connection between the connecting rod 27 and the drive arm 22.

To maintain the adjusted connection wherever it is established by the operator, any suitable clamping means may be used. In the execution of the invention shown in the drawings, the shaft of the adjusting crank is made hollow and the adjusting pinion 25 is likewise made hollow so that a long bolt 40 may pass through one of the arms of the yoke 26, through the pinion 25, through the shaft of the adjusting crank and into threaded engagement with a clamp member 41. The clamp member 41 has outwardly projecting, relatively long arms 42 so that it may be clamped in place with substantial force by the operator. When the clamp 41 is tightened down, it .bears against an adjacent portion of the adjusting crank and clamps a face 43 of the crank against the adjacent side of the yoke 26 and, at the same time, forces the nut 40 tightly [against the opposite arm of the yoke 26. This clamps the drive arm 22 between the arms of the yoke and maintains the adjusted position of the pinion, and thus the connecting rod 27 with respect to the drive arm 22.

At its lower end the connecting rod 27 engages an eccentric 50 (FIG. 1) carried on a plate 52 which is keyed or otherwise fixed to a drive shaft extending from a reduction gear 53 driven by a motor 54.

The motor assembly, comprising not only the motor 54 but the gear reducer and eccentric 52 are all carried by a motor base 56. As shown in FIG. 8 the motor base 56 is provided with laterally extending flanges 58 which engage under gibs or guides 59 on an inclined support 60. The motor base is provided with a nut 61 meshing with an adjusting lead screw 62 having a handle 63 at its exposed end. Thus, as the handle 63 is turned the lead screw 62 will move the motor base inwardly and outwardly along the guide members 59 and thus adjust the location of the motor and drive assembly with respect to the support 12 and the fulcrum or bearing 20 on which the lower insulating arm 13 and the drive arm 22 are mounted. The support 60 is made as an inclined plane, although ideally it would be arcuate with respect to the fulcrum 20. Adjustment of the eccentric and associated mechanism upwardly and downwardly on the inclined plane is referred to as an adjustment about the fulcrum in defining the invention in the appended claims.

The mechanism so far described provides for two major adjustments of the motion of the gun stem 16. As shown in FIG. 4 the extent of the stroke of the stem 16 may be changed or adjusted without making any great change in the position of the mid-point of the reciprocatory stroke. This follows largely because of the arcuate configuration of the drive arms 22 which is concave about a center near the neutral position of adjustment of the drive means. Further, as shown in FIG. 5, the center line, or the location of the mid-point of the stroke of the stem 16 may also be adjusted While maintaining essentially the same length of reciprocation of the stem 16.

Both of the adjustments indicated in FIG. 4 and FIG. can be made on the fly; that is while the stem 16 is in operation. It has been found that a reciprocatory movement having a frequency of approximately 60 cycles per minute is satisfactory for the motion to be imparted to the stem 16 in an electrostatic spraying system. With the reciprocating parts moving at this frequency it is a rather simple matter for the operator to release the clamping force on crank 39 by turning the nut handles 42 and releasing theclamp nut 41. With the clamp nut 41 satisfactorily released, the crank 39 may be used to turn the pinion 25 to a new location on the drive arm 22. This motion will change the extent of the stroke of the stem 16 but will not significantly alter the center or mid-point of the stroke. When the stroke has been changed to the desired extent, the operator holds the crank 39' in the adjusted position while tightening the clamp nut 41, thus forcing the sides of the yoke against the flanks or faces of the drive arm 22. The adjusted position of the parts will thus be maintained.

As shown in FIG. 4, assuming that the eccentric 52 has not changed its location the effective limits of the stroke may be changed by moving the point of connection to the drive arm 22 between points designated A and B. When the effective length of the lever arm of the system is short, as when point A on the driving side of the stem approaches the fulcrum 20 the stroke of the stem 16 will be long, between the limits shown by the dimension designation A in FIG. 4. When the adjustment is changed so that the connecting rod 27 effectively engages the drive arm 22 towards the rear end thereof, the lever arm represented by the drive arm 22 is long with relation to the fulcrum 20 and'the stroke of the stem 16 is thus shortened. The dimension line B in FIG. 4 essentially indicates the diminished stroke. It will be seen from an .inspection of FIG. 4 that the center 'line of the reciprocatory motion has not been changed to any significant extent by this adjustment. The fact that the parts are moving during the time this adjustment is made does not interfere with the ease of adjustment at a normal operating frequency.

The adjustment of the location of the midpoint of the reciprocatory stroke is indicated by the diagram in FIG. 5. During this adjustment, the location of the connection to the drive arm 22 remains stationary and adjustment is made in the location of the center of the drive eccentric 52. This is done by moving the motor base in and out to move along its guides 59 closer to or farther from the support 12 on which the fulcrum 20 is located. In FIG. 5, a neutral position is indicated at O and the center line of this position is shown in full lines on the intersection between the lower arm 13 and the stem 16. This center line can be moved down (indicated by the sign) by moving the motor and its drive mechanism upwardly on the inclined plane represented by the base 60. This is done, of course, by rotation of handle 63 and lead screw 62. If the motor base is moved inwardly towards the support 12, the center of the reciprocatory stroke is moved upwards to the position as indicated in FIG. 5. This adjustment will be made if the parts to be sprayed have a higher center than normal, and conversely the adjustment will be made in the lowered or direction if the parts have a lower center than normal. When it is desired to increase or decrease the extent of the stroke to accommodate the changing characteristics of the parts presented to the spraying sysem, the adjustment indi cated in FIG. 4 will be made, as above noted.

The stem 16 carries a plurality of electrostatic spray guns G, and the guns may be adjustably mounted in any suitable manner. Preferably, the stem 16 is perforated at intervals as indicated by the openings in FIG. 7. The spray guns themselves are mounted on rods 102 that extend rearwardly and pass through mounting blocks 104. A set screw 105 intersects the opening through which the rods pass and an enlarged head 106 on the set screw will permit the maintenance of an adjustment of the position of the gun carrying rod.

The mounting block 104 is held slidably adjacent the stem 16 by a U-shaped strap 107 that is bolted to the block and surrounds the stem 16. A detent 108 is provided in the block and is urged inwardly by a spring 109 so that the detent enters one of the openings in the stem to maintain the vertical adjustment of the gun mount. A handle 110 is provided for the detent and, by pulling out on the handle, the operator can adjust the vertical position of the gun mount, within the limits defined by the spacing of the openings 100 that are formed in the stem. It will be apparent that any suitable gun mounting mechanism may be used.

In operation, the reciprocatory movement of the stem 16 is imparted by the motor 54 through the reduction gear 53 and the eccentric 52 to the connecting rod 27. A clamp connection as above described is made between the connecting rod drive mechanism and the lever provided by the arcuate drive arm 22. As this end of the lever is reciprocated vertically about the pivot point 20 the lower insulating arm 13 is reciprocated. The stem 16, while driven by the lower insulating arm 13 is confined in its reciprocatory movement by the upper arm 14 so that its resultant movement is essentially vertical.

The extent of the stroke imparted to the stem 16 and hence to the guns may be adjusted by the mechanism originating in crank 39 while the center position of the reciprocating stroke is adjusted by turning the motor base assembly in and out through lead screw 62. By these two adjustments, changes in the spray location may be made to accommodate the coating of parts of varying height and varying location with respect to the spraying mechanism without shutting the machine down.

As previously noted, the reciprocating mechanism is especially suited for blending the spray patterns of a plurality of associated electrostatic spray guns.

While the invention has been disclosed in conjunction with a specific form and disposition of the parts, it should be expressly understood that numerous modifications and changes may be made without departing from the scope of the appended claims. For example, the configuration of the re arwardly extending drive arm 22 may be changed from an arcuate configuration to a straight configuration. This change will lead -to a simultaneous change of stroke height and stroke midpoint which may, under many circumstances, be readily tolerated. Further, if a more precise adjustment is required it can be obtained by making the path of adjustment of the motor base 56 arcuate instead of straight as shown in the drawings. The center of the arc would be on the center of the fulcrum 20. Most commercial painting installations require that the orientation of the stem 11 and the reciprocation of the spray guns be along a vertical path. In unusual installations, however, it may be desirable to reciprocate the guns along inclined or horizontal paths. Such a modification is within the scope of the invention as defined by the appended claims.

What we claim is:

1. A mechanism for reciprocating an electrostatic spray gun or the like comprising a frame, spaced parallel arms pivoted on spaced points on said frame, a gun mounting stem connecting said arms, one of said arms extending on the opposite side of said frame to provide a driving lever for said stem fulcrumed on said frame, drive means to reciprocate said driving lever, said drive means comprising a drive motor, an eccentric driven by said motor, and a connecting rod connecting said eccentric and said driving lever, and means to move said drive motor and eccentric in an inclined direction with respect to said frame to raise and lower said eccentric with respect to said fulcrum to vary the midpoint of said reciprocating movement without significantly changing the length of said reciprocating stroke.

2. A mechanism for reciprocating an electrostatic spray gun or the like comprising a frame, spaced parallel arms pivoted on spaced points on said frame, said arms being of equal length, a gun mounting stem connecting said arms and held thereby in a position parallel to said frame, one of said arms extending on the opposite side of said frame to provide a driving lever for said stem fulcrumed on said frame, drive means to reciprocate said driving lever comprising a drive motor, an eccentric driven by said motor and a connecting rod between said eccentric and said driving lever, a releasable clamp connection between said connecting rod and said driving lever whereby said driving means is adjustable towards and away from said fulcrum to vary the length of the reciprocating stroke of said stem, additional means to adjust said drive means by moving said motor with respect to said fulcrum to vary the midpoint of said reciprocating movement without significantly changing the length of said reciprocating stroke, and said driving lever being arcuate about a center near the midpoint of the adjustment of said additional means whereby changing the point of connection between said connecting rod and said driving lever does not significantly change the midpoint of the reciprocating stroke of said stem, but affects only the effective length of said driving lever with respect to said fulcrum.

3. A mechanism for reciprocating an electrostatic spray gun or the like comprising a frame, spaced parallel arms pivoted on spaced points on said frame, a gun mounting stem connecting said arms, one of said arms extending on the opposite side of said frame to provide a driving lever for said stem fulcrumed on said frame, drive means ineluding a connecting rod to reciprocate said driving lever, means to adjust the point of connection between said connecting rod and said driving lever towards and away from said fulcrum to vary the length of the reciprocating stroke of said stem, and additional means to adjust the position of the driven end of said connecting rod about said fulcrum to vary the midpoint of said reciprocating movement without significantly changing the length of said reciprocating stroke, said driving lever being arcuate about a center near the midpoint of the adjustment of said additional means.

References Cited by the Examiner UNITED STATES PATENTS 272,392 2/1883 Wheeler 74-586 X 622,257 4/1899 Pavia 74--586 X 720,594 2/1903 Macarthy 118-323 725,606 4/1903 Thompson 74586 X 1,123,129 12/1914 Kirkpatrick 173-148 X 1,919,798 7/1933 MacLaurin 118-323 X 2,197,730 4/1940 Mugford 7441 2,764,956 10/1956 Burnett et a1 118-323 X 2,873,611 2/1959 Biermann 74-40 FOREIGN PATENTS 191,131 11/1907 Germany.

MILTON KAUFMAN, Primary Examiner.

BROUGHTON G. DURHAM, FRED C. MATTERN,

JR., Examiners.

D. H. THIEL, Assistant Examiner. 

3. A MECHANISM FOR RECIPROCATING AN ELECTROSTATIC SPRAY GUN OR THE LIKE COMPRISING A FRAME, SPACED PARALLEL ARMS PIVOTED ON SPACED POINTS ON SAID FRAME, A GUN MOUNTING STEM CONNECTING SAID ARMS, ONE OF SAID ARMS EXTENDING ON THE OPPOSITE SIDE OF SAID FRAME TO PROVIDE A DRIVING LEVER FOR SAID STEM FULCRUMED ON SAID FRAME, DRIVE MEANS INCLUDING A CONNECTING ROD TO RECIPROCATE SAID DRIVING LEVER, MEANS TO ADJUST THE POINT OF CONNECTION BETWEEN SAID CONNECTING ROD AND SAID DRIVING LEVER TOWARDS AND AWAY FROM SAID FULCRUM TO VARY THE LENGTH OF THE RECIPROCATING STROKE OF SAID STEM, AND ADDITIONAL MEANS TO ADJUST THE POSITION OF THE DRIVEN END OF SAID CONNECTING ROD ABOUT SAID FULCRUM TO VARY THE MIDPOINT OF SAID RECIPROCATING MOVEMENT WITHOUT SIGNIFICANTLY CHANGING THE LENGTH OF SAID RECIPROCATING STROKE, SAID DRIVING LEVER BEING ARCUATE ABOUT A CENTER NEAR THE MIDPOINT OF THE ADJUSTMENT OF SAID ADDITIONAL MEANS. 